A bag contains $5$ red balls, $10$ green balls, and $4$ blue balls. If a ball is randomly chosen, what is the probability that it is not green?
Answer: There are $5 + 10 + 4 = 19$ balls in the bag. There are $10$ green balls. That means $19 - 10 = 9$ are not green. The probability is $ \frac{9}{19}$.